1. Field of the Invention
The present invention relates to well completion. More specifically, the invention relates to apparatus and methods for isolation of multiple zones of interest in a wellbore.
2. Background Art
It is often desirable to isolate portions of a well. For example, separate zones may be isolated from one another in order to separately control production from the zones or portions of a zone may be isolated to prevent or reduce production of water.
Isolation in an open hole is typically accomplished with external casing packers (ECP), which are inflatable packers. In a typical completion operation, the ECP is run with a completion string downhole. An inflate service tool may be run with the ECP or on a separate trip. Cement, mud, or some other type of fluid is then pumped into the packer for inflation. The fluids pumped into the packer are trapped inside the packer, which is a closed chamber once the inflation port is shut off.
Generally, the inflation pressure trapped in the packer is initially higher than the formation pressure in order to maintain positive contact with the wall of the well. However, the inflation pressure may decrease for various reasons such as cooling down during injection or production, an increase in the borehole size as a result of formation depletion or borehole wall deterioration, or a leak in the packer. In these cases, the packer may lose contact with the borehole wall and stop providing the desired isolation.
With current packer systems, a loss of seal between the packer and the casing or formation wall may not be repairable or may require numerous remedial trips into the well, resulting in increased risk of blow out, loss of production, or increased damage to zones of interest due to long or repetitive shut-in. Remedial operations are extremely expensive and time-consuming. A need, therefore, exists for improved methods and apparatus for providing isolation and other functionality in a well.